Composition of a polyphenylene ether, a block copolymer of a vinyl aromatic compound and a conjugated diene and a polyolefin

ABSTRACT

There are provided compositions comprising a polyphenylene ether and a synergistic combination comprising an elastomeric block copolymer of a vinyl aromatic compound and a conjugated diene and a polyolefin resin, optionally containing a styrene homopolymer or random copolymer resin. The addition of the combination of elastomeric block copolymer resin and polyolefin resin to polyphenylene ethers or mixtures of polyphenylene ethers and such polystyrenes provides unexpected improvements in toughness in parts molded from the composition, in comparison with compositions containing either the block copolymer or the polyolefin resin alone.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of copending application Ser. No. 67,358,filed Aug. 17, 1979, which, in turn, is a division of Ser. No. 839,106,filed Oct. 3, 1977, now U.S. Pat. No. 4,166,055.

This invention relates to novel resin compositions and moreparticularly, to polymer compositions comprising a polyphenylene ether,a combination comprising an elastomeric block copolymer of a vinylaromatic compound and a conjugated diene and a polyolefin resin and,optionally, a polystyrene homopolymer or random copolymer resin.

BACKGROUND OF THE INVENTION

The polyphenylene ethers are known and described in numerouspublications including Hay, U.S. Pat. No. 3,306,874 and 3,306,875 andStamatoff 3,257,357 and 3,257,358. The high molecular weightpolyphenylene ethers are high performance engineering thermoplasticspossessing relatively high melt viscosities and softening points--i.e.,in excess of 275° C., and are useful for many commercial applicationsrequiring high temperature resistance including formation of films,fibers and molded articles.

Although they have the above-described desirable properties, it is alsoknown that certain properties of the polyphenylene ether resins areundesirable for some commercial uses. For example, parts molded from thepolyphenylene ethers are somewhat brittle due to poor impact strength.In addition, the relatively high melt viscosities and softening pointsare considered a disadvantage for many uses. Films and fibers can beformed from polyphenylene ether resins on a commercial scale usingsolution techniques, but melt processing is commercially unattractivebecause of the high temperatures required to soften the resin and theproblems associated therewith such as instability, discoloration and therequirement for specially designed process equipment to operate atelevated temperatures. Molded articles can be formed by melt processingtechniques, but, again, the high temperatures required are undesirable.

It is known in the art that properties of the polyphenylene ether resinscan be materially altered by blending them with other resins. Forexample, in commonly-assigned patent, U.S. Pat. No. 3,361,851, apolyphenylene ether composition comprising a polyphenylene ether blendedwith a polyolefin is disclosed. The polyolefin is added to improveimpact strength and resistance to aggressive solvents. In a secondcommonly assigned patent, Cizek, U.S. Pat. No. 3,383,435, there areprovided means for simultaneously improving the melt processability ofthe polyphenylene ether resins while simultaneously up-grading manyproperties of polystyrene homopolymer and random copolymer resins. Theinvention of the Cizek patent is based upon the discovery that thepolyphenylene ether resins and such polystyrene resins, including rubbermodified polystyrene resins, are combinable in all proportions andresult in compositions having many properties improved over those ofeither of the components. When polyethylene is incorporated inpolyphenylene ether or in compositions thereof with styrene resins, meltflow and physical properties are markedly improved. The amount ofpolyolefin which can be incorporated is limited, however, to about 5parts per hundred of resin, due to excessive delamination andaccompanying brittleness.

It has also been disclosed, see commonly assigned U.S. Pat. No.3,994,856, and application Ser. No. 387,588, filed Aug. 13, 1973,abandoned in favor of application Ser. No. 826,196 filed Aug. 19, 1977that an elastomeric block copolymer of a vinyl aromatic compound (A) and(A)¹ and a conjugated diene (B), of the A-B-A¹ type, A and A¹ being thesame or different, and the molecular weight of the center block beinghigher than that of the terminal blocks, or a hydrogenated derivativethereof, will impart unexpectedly high impact strengths and chemicalresistance properties both to polyphenylene ether resins andcompositions of polyphenylene ether resins and polystyrene homopolymerand random copolymer resins. These applications are incorporated hereinby reference.

It has now been discovered that much higher amounts of polyolefin can beincorporated if a block copolymer is also incorporated in thecomposition. Most unexpected is a tremendous synergistic increase inIzod impact strength following use of the combination of polyolefin andblock copolymer. A small amount of a plasticizer provides furtherenhancement of impact strength.

DESCRIPTION OF THE INVENTION

According to the present invention there are provided thermoplasticcompositions, having high impact strength comprising

(a) a polyphenylene ether resin or a composition comprising apolyphenylene ether resin and a styrene homopolymer or random copolymerresin and

(b) a synergistic, impact strength improving combination comprising (i)an elastomeric block copolymer of a vinyl aromatic compound (A) and (A)¹and a conjugated diene (B), of the A-B-A¹ type, the center block B beingof higher molecular weight than that of the combined terminal blocks Aand A¹ or a hydrogenated derivative thereof and (ii) a polyolefin resin,component (b) being present in an amount of from about 5 to about 30% byweight of the total resinous components of the composition.

Preferred compositions will be those in which the polyphenylene ethercomprises at least 1% by weight of the total resinous components in thecomposition.

It is to be understood, however, that the present compositions can alsoinclude conventional amounts of conventional additives forprocessability, flame retardancy, stability and the like.

Among the features of this invention are reinforced compositionscontaining reinforcing amounts of reinforcements, such as powders,whiskers, fibers or platelets of metals, e.g., aluminum, bronze, iron ornickel, and non-metals, e.g., carbon filaments, acicular CaSiO₃,asbestos, TiO₂ titanate whiskers, glass flakes and fibers and the like.Such reinforcements will be present in an amount of, e.g., 2 to 90% byweight, preferably 10 to 60% by weight. Especially preferred as areinforcement is fibrous glass.

In preferred compositions the polyphenylene ether resins in component(a) will be those having repeating structural units of the formula##STR1## wherein the oxygen ether atom of one unit is connected to thebenzene nucleus of the next adjoining unit, n is a positive integer andis at least 50, and each Q is a monovalent substituent selected from thegroup consisting of hydrogen, halogen, hydrocarbon radicals,halohydrocarbon radicals having at least two carbon atoms between thehalogen atom and the phenyl nucleus, hydrocarbonoxy radicals, andhalohydrocarbonoxy radicals having at least two carbon atoms between thehalogen atom and phenyl nucleus. The preparation of polyphenylene etherresins corresponding to the above formula is described in theabove-mentioned patents of Hay and Stamatoff. Especially preferredpolyphenylene ether resins for purposes of the present invention arethose having alkyl substitution in the two positions ortho to the oxygenether atom--i.e., where each Q is alkyl, most preferably, having from 1to 4 carbon atoms. The most preferred polyphenylene ether resin forpurposes of the present invention ispoly(2,6-dimethyl-1,4-phenylene)ether (each Q is methyl).

The block copolymers of a vinyl aromatic hydrocarbon and a dienehydrocarbon (b) (i) are well known in the art and commerciallyavailable. These are described, for instance, in "Polymer Chemistry ofSynthetic Elastomers", edited by Kennedy et al, Interscience Publishers,Vol. 23, Part II (1969), pages 553-559, the disclosure of which isincorporated herein by reference. Other descriptions are given inZelinski, U.S. Pat. No. 3,251,905, and Holden et al, U.S. Pat. No.3,231,635 which are also incorporated herein by reference.

In general, component (b) (i) is a block copolymer of the A-B-A type inwhich terminal blocks A, which can be the same or different, arethermoplastic homopolymers or copolymers prepared from a vinyl aromaticcompound wherein the aromatic moiety can be either mono- or polycyclic.Examples include styrene, alpha-methyl styrene, vinyl toluene, vinylxylene, ethyl vinyl xylene, vinyl naphthalene and the like, or mixturesthereof.

Center block B is an elastomeric polymer derived from a dienehydrocarbon, preferably a conjugated diene, e.g., 1,3-butadiene,2,3-dimethyl butadiene, isoprene, 1,3-pentadiene, and the like, ormixtures thereof.

The ratio of the copolymers and the average molecular weights of eachcan vary broadly. Frequently however, the molecular weight of centerblock B will be greater than that of the continued terminal blocks,which appear to be necessary for optimum impact strength and solventresistance. The molecular weight of terminal block A will preferablyrange from about 2,000 to about 100,000, while the molecular weight ofcenter block B is preferably from about 25,000 to about 1,000,000.

If desired, the block copolymers can be post-treated to hydrogenate therubber portion of the copolymer.

Hydrogenation can be carried out in a variety of hydrogenate catalysts,such as nickel on Kieselguhr, Runey nickel, copper chromate, molybdenumsulfide and finely divided platinum or other noble metals on a lowsurface area catalyst.

Hydrogenation can be conducted at any desired temperature or pressure,e.g., from atmospheric to 3,000 p.s.i.g., usually between 100 and 1,000p.s.i.g., and at temperatures between 75° to 600° F., for times rangingbetween 0.1 and 24 hours, preferably from 0.2 to 8 hours.

With respect to the hydrogenated A-B-A block copolymers, it is preferredto form terminal block A having average molecular weight of from about4,000 to about 115,000 and center block B having an average molecularweight of from about 20,000 to about 450,000. Still more preferably, theterminal block A will have an average molecular weight of from 8,000 to60,000 while center block B still have an average molecular weight offrom 50,000 to 300,000.

The terminal block will also preferably comprise from 2 to 33% byweight, more preferably from 5 to 30% by weight, based on the totalweight of the block copolymer (b) (i).

Especially preferred hydrogenated block copolymers are those having apolybutadiene center block wherein from 35 to 55%, more preferably from40 to 50% of the butadiene carbon atoms are vinyl side chains.

The hydrogenated block copolymers are described further in Jones, U.S.Pat. Nos. 3,431,323 and De LaMare et al, 3,670,054, both of which areincorporated herein by reference.

In preferred compositions, component (b) (i) will be an A-B-A blockcopolymer of the polystyrene-polybutadiene-polystyrene orpolystyrene-polyisoprene-polystyrene type wherein the polybutadiene orpolyisoprene portion can be either hydrogenated or non-hydrogenated.

As noted above, the polyolefin resin can include polyethylene,polypropylene, copolymers of ethylene and propylene, polyisobutylene,and the like. They are commercially available or can be prepared bymethods well known to those skilled in the art. Polyethylene ispreferred. The amounts of (b), the synergistic combination, willgenerally vary between 5 and 25% by weight of the total resinouscomponents of the composition. The upper limit is determined in eachcase by checking to see that the additive does not segregate out into aseparate phase during molding. Too much will end in delamination and atendency to weaken the molded work pieces.

In a preferred feature, a plasticizer will be included with thecomposition of polyphenylene ether, block copolymer and polyolefinresin. The plasticizer appears to enhance mixing and preventspreferential association of regions of the same polymer. Generally, anyplasticizer which is compatible with both polyphenylene ether, blockcopolymer and polyolefins may be used. Typical examples of suitableplasticizers are chlorinated biphenyls, mineral oil, phosphates, and thelike. Preferably, triphenyl phosphate will be used.

The amount of plasticizer should be kept at a level which will notunduly diminish properties of the polymer, i.e., rigidity, heatdistortion, etc. In general up to about 25% of plasticizer based ontotal resinous components will be used.

As noted above, the elastomeric block copolymer and the polyolefin resinmay be added to a polyphenylene ether resin or to a composition of apolyphenylene ether resin with an additional resin, preferably apolystyrene homopolymer or random copolymer resin and most preferably, ahigh impact polystyrene resin. As disclosed in the above-mentioned Cizekpatent, the styrene resin most readily combinable with the polyphenyleneether resin is one having at least 25% by weight polymer units derivedfrom vinyl aromatic monomer having the formula ##STR2## where R ishydrogen, alkyl of 1 to 4 carbon atoms or halogen; Z is a memberselected from the class consisting of vinyl hydrogen, or alkyl of from 1to 4 carbon atoms; and p is from 1 to 5. Such compositions will comprisefrom 1 to 99% by weight of the polyphenylene ether component and from 99to 1% by weight of the polystyrene resin. The preferred styrene resinfor purposes of this invention is one comprising either a styrenehomopolymer or a rubber modified polystyrene, e.g., blended or graftedwith from about 3 to 30, preferably from 4 to 12% by weight of apolybutadiene or a rubbery random copolymer, e.g., of about 70% BD and30% styrene.

The amount of elastomeric block copolymer and polyolefin resin added tothe polyphenylene ether resin or composition thereof with polystyrenemay vary within rather broad limits, but preferably ranges from about 5to 30% by weight of the resinous components.

In a preferred family of compositions the polyphenylene ether comprisesfrom about 1 to about 90% by weight, the elastomeric block copolymer ofa vinyl aromatic compound and a conjugated diene, or hydrogenatedderivative thereof, and polyolefin resin comprises from about 5 to about30% by weight, and the styrene homopolymer or random copolymer resincomponent comprises from 0 to the remainder by weight of the totalweight of the resinous components in said composition. Especiallypreferred are compositions in which the polyphenylene ether ispoly(2,6-dimethyl-1,4-phenylene)ether and comprises from about 20 toabout 90% by weight, component (b) (i) is an elastomeric block copolymerof styrene and butadiene of the poly(styrene-butadiene-styrene) type ora hydrogenated derivative thereof, (b) (i) is polyethylene and (b) (i)and (ii) together comprise from about 5 to about 30% by weight and thestyrene homopolymer or random copolymer resin component is a rubbermodified polystyrene and comprises from 0 to up to about 60% by weightof the total weight of the resinous components in the composition.

It should be obvious that other additives may be present in thecompositions such as pigments, flame retardants and stabilizers inamounts varying between about 1 and 30 percent by weight of the totalcomposition. The above-stated range for the elastomeric block copolymerresin, the polyolefin resin the polyphenylene ether resin, and, ifpresent, the polystyrene resin, is based solely upon such resinouscomponents in the polymer blend and excludes other additives.

The method of forming the polymer composition is not critical, prior artblending techniques being suitable. The preferred method comprisesblending the polymers and additives, such as reinforcements in powder,granular and filamentous form--as the case may be--extruding the blendand chopping into pellets suitable for molding to shape by meansconventionally used to mold normally solid thermoplastic compositions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The advantages obtained by providing compositions of an elastomericvinyl aromatic, conjugated diene A-B-A¹ block copolymer resin andpolyolefin with a polyphenylene ether resin alone or in combination withanother resin are illustrated in the following examples which are setforth as further description of the invention, but are not to beconstrued as limiting the invention thereto.

EXAMPLES 1 and 2

The formulations are mechanically blended then coextruded in a 28 mmWerner-Pfleiderer-twin screw extruder and molded into test pieces in a 3oz. Newbury injection molding machine. The molded articles are subjectedto standard testing. The formulations and properties are set forth inTable 1:

                  TABLE 1                                                         ______________________________________                                        Compositions of Polyphenylene Ether                                           Rubber-Modified Polystyrene, A-B-A                                            Block Copolymer and Polyolefin                                                Example          1       2       1A*   2A*                                    ______________________________________                                        Composition (parts by wt.)                                                    Poly(2,6-dimethyl-1,4-                                                        phenylene ether.sup.a                                                                          80      80      80    80                                     Rubber modified poly-                                                         styrene.sup.b    20      20      20    20                                     Styrene-butadiene-                                                            styrene block copolymer.sup.c                                                                  5       5       5     --                                     Polyethylene.sup.d                                                                             3       3       --    3                                      Triphenyl phosphate                                                           (plasticizer)    --      2       --    --                                     Properties                                                                    Tensile yield, psi                                                                             9,800   9,800   11,500                                                                              11,900                                 Izod impact, ft.lbs./in.                                                      notch            11.6    13.4    2.4   1.1                                    Gardner impact, in.-lbs.                                                                       250     270     300   73                                     ______________________________________                                         *Control                                                                      .sup.a PPO, General Electric Co.                                              .sup.b Polystyrenebutadiene graft 834,Foster Grant                            .sup.c Kraton G6521,Shell Polymers Co. Hydrogenated B block                   .sup.d AC1702, Allied Chemical Co.                                       

The use of a combination of block copolymer and polyolefin is seen tocause a synergistic increase in notched Izod impact strength.

EXAMPLES 3-5

The general procedure of Examples 1 and 2 is repeated with a highloading of plasticizer and no rubber modified polystyrene. Theformulation and properties are set forth in Table 2:

                  TABLE 2                                                         ______________________________________                                        Compositions of Polyphenylene Ether,                                          Plasticizer, A-B-A Block Copolymer                                            And Polyolefin Resin                                                          Example           3A*     3       4     5                                     ______________________________________                                        Composition (pasts by wt.)                                                    Poly(2,6-dimethyl-1,4-pheny-                                                  lene ether.sup.a  78      78      78    78                                    Triphenyl phosphate                                                           (plasticizer)     22      22      22    22                                    Styrene-butadiene-styrene                                                     block copolymer.sup.b                                                                           --      15      15    10                                    Polyethylene      7.5     7.5     10    7.5                                   Properties                                                                    Tensile elongation, %                                                                           19      84      79    66                                    Izod impact, ft.-lbs./in.notch                                                                  2.0     21.0    21.3  22.8                                  Gardner impact, in.-lbs.                                                                        <10     161     162   182                                   ______________________________________                                         *Control                                                                      .sup.a PPO, General Electric Co.                                              .sup.b Hydrogenated B block, Kraton KG6521, Shell Polymers               

It is seen that high amounts of polyolefin can be incorporated withoutembrittlement if the hydrogenated A-B-A block copolymer is alsoincorporated.

EXAMPLES 6-8

The general procedure of Examples 1-2 is repeated, substituting an A-B-Ablock copolymer that is not hydrogenated. The formulations andproperties are set forth in Table 3:

                  TABLE 3                                                         ______________________________________                                        Compositions of Polyphenylene Ether,                                          Rubber Modified Polystyrene, Plasticizer,                                     A-B-A Block Copolymer and Polyolefin Resin                                    Example          6A*     6       7     8                                      ______________________________________                                        Composition (parts by wt.)                                                    Poly(2,6-dimethyl-1,4-                                                        phenylene)ether.sup.a                                                                          35      35      35    35                                     Rubber modified polystyrene.sup.b                                                              65      65      65    65                                     Triphenyl phosphate                                                           (plasticizer)    8       8       8     8                                      Styrene-butadiene-styrene                                                     block copolymer.sup.c                                                                          --      15      15    15                                     Polyethylene     5       5       10    15                                     Properties                                                                    Tensile yield, psi                                                                             6,300   5,800   5,400 4,900                                  Tensile strength, psi                                                                          6,200   6,000   5,800 5,200                                  Elongation, %    47      79      80    56                                     Izod impact, ft.-lbs./in.notch                                                                 4.4     10.3    10.7  10.6                                   Gardner impact, in.-lbs.                                                                       10      202     151   135                                    Flexural modulus, psi                                                                          290,000 246,000 228,000                                                                             203,000                                Flexural strength, psi                                                                         7,200   6,800   6,300 5,900                                  ______________________________________                                         *Control                                                                      .sup.a PPO, General Electric Co.                                              .sup.b FG 834, Foster Grant Co.                                               .sup.c Kraton K1011, Shell Polymers Co., not hydrogenated                

It is seen that the present invention permits the use of large amountsof polyolefin without detrimental loss of impact properties.

EXAMPLES 8-9

The procedure of Examples 1 and 2 is repeated, except using a mixture ofan hydrogenated A-B-A block copolymer and an unhydrogenated A-B-A blockcopolymer. The compositions and properties are summarized in Table 4.

                  TABLE 4                                                         ______________________________________                                        Compositions Comprising a Poly-                                               phenylene Ether Resin, a Rubber                                               Modified High Impact Polystyrene,                                             A-B-A Block Copolymers and Poly-                                              ethylene                                                                      Composition,                                                                  parts by weight  9       10      B*    C*                                     ______________________________________                                        poly(2,6-dimethyl-1,4-                                                        phenylene)ether.sup.a                                                                          35      35      35    35                                     rubber modified high                                                          impact polystyrene.sup.d                                                                       65      65      65    65                                     hydrogenated styrene-                                                         butadiene-styrene block                                                       copolymer.sup.e  7.5     7.5     --    --                                     unhydrogenated styrene-                                                       butadiene-styrene block                                                       copolymer.sup.c  7.5     7.5     --    --                                     polyethylene     5       10      --    5                                      triisopropylphenyl                                                            phosphate.sup.f  8       8       8     8                                      Properties                                                                    Izod impact, ft.lbs./                                                         in.notch         8.6     9.7     3.4   4.7                                    Gardner impact, in./lbs.                                                                       190     70      60    20                                     ______________________________________                                         *comparison experiment                                                        .sup.a PPO, General Electric Company                                          .sup.c Kraton K 1011, Shell Chemical Company                                  .sup.d A6H6, Arco Polymers, Inc.                                              .sup.e Kraton G 1651, Shell Chemical Company                                  .sup.f Kronitex 50, FMC Co.                                              

Obviously, other modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that changes may be made in the particular embodiments of theinvention described which are within the full intended scope of theappended claims.

I claim:
 1. A thermoplastic composition, having high impact strength,comprising(a) a polyphenylene ether resin or a composition comprising apolyphenylene ether resin and a styrene homopolymer or random copolymerresin and (b) a synergistic, impact strength-improving combinationcomprising (i) a mixture of an elastomeric block copolymer of a vinylaromatic compound (A) and (A)¹ and a conjugated diene (B), of the A-B-A¹type, the center block B being of higher molecular weight than that ofthe combined terminal blocks A and A¹ and a hydrogenated derivativethereof and (ii) a polyolefin resin, component (b) being present in anamount of from about 5 to about 30% by weight of the total resinouscomponents of the composition.
 2. A composition as defined in claim 1wherein component (a) is a polyphenylene ether of the formula ##STR3##wherein the oxygen ether atom of one unit is connected to the benzenenucleus of the next adjoining unit; n is an integer of at least 50; andeach Q is a monovalent substituent selected from hydrogen, halogen,hydrocarbon radicals, halohydrocarbon radicals having at least twocarbon atoms between the halogen atom and the phenyl nucleus,hydrocarbonoxy radicals, and halohydrocarbonoxy radicals having at leasttwo carbon atoms between the halogen atom and the phenyl nucleus.
 3. Acomposition as defined in claim 2 wherein each Q is alkyl having from 1to 4 carbon atoms.
 4. A composition as defined in claim 2 wherein each Qis methyl.
 5. A composition as defined in claim 2 wherein saidpolyphenylene ether comprises at least 1% by weight of the totalresinous components in said composition.
 6. A composition as defined inclaim 1 wherein, in component (b)(i), (A) and (A)¹ are selected fromstyrene, α-methyl styrene, vinyl toluene, vinyl xylene and vinylnaphthalene and (B) is selected from butadiene, isoprene, 1,3-pentadieneor 2,3-dimethylbutadiene.
 7. A composition as defined in claim 6wherein, in component (b)(i), (A) is a styrene block, (B) is a butadieneblock and (A)¹ is a styrene block.
 8. A composition as defined in claim7 wherein, in component (b)(i), terminal blocks A and A¹ have molecularweights of 2,000 to 100,000, respectively, and center block B has amolecular weight of from 25,000 to 1,000,000.
 9. A composition asdefined in claim 1 wherein the hydrogenated derivative of component(b)(i) has been hydrogenated to reduce the unsaturation of block B toless than 10% of the original unsaturation.
 10. A composition as definedin claim 1 wherein polyolefin component (b)(ii) is polyethylene, acopolymer of ethylene and propylene, polypropylene, polyisobutylene, ora mixture of any of the foregoing.
 11. A composition as defined in claim10 wherein polyolefin component (b)(ii) is polyethylene.
 12. Acomposition as defined in claim 1 wherein component (a) comprises(i)from 1 to 99% by weight of a polyphenylene ether of the formula ##STR4##where Q is alkyl of from 1 to 4 carbon atoms and n is an integer of atleast 50 and (ii) from 99 to 1% by weight of a styrene homopolymer orrandom copolymer resin having at least 25% of the polymer units derivedfrom a vinyl aromatic compound of the formula ##STR5## wherein R ishydrogen, alkyl of from 1 to 4 carbon atoms or halogen, Z is hydrogen,alkyl of from 1 to 4 carbon atoms or vinyl and p is 0 or an integer offrom 1 to
 5. 13. A composition as defined in claim 12 wherein thestyrene resin is a styrene homopolymer resin or a rubber modifiedstyrene resin, said rubber comprising a diene rubber or a rubberycopolymer of butadiene and styrene in an amount of from about 4 to about12% by weight of said resin.
 14. A composition as defined in claim 12wherein the polyphenylene ether ispoly(2,6-dimethyl-1,4-phenylene)ether.
 15. A composition as defined inclaim 1 wherein the polyphenylene ether comprises from about 1 to about90% by weight, the synergistic combination (b) comprising (i) a mixtureof an elastomeric block copolymer of a vinyl aromatic compound and aconjugated diene and a hydrogenated derivative thereof and (ii) apolyolefin resin comprises from about 5 to about 30% by weight, and thestyrene homopolymer or random copolymer resin component comprises from 0to the remainder by weight of the total weight of the resinouscomponents in said composition.
 16. A composition as defined in claim 15wherein said polyphenylene ether ispoly(2,6-dimethyl-1,4-phenylene)ether and comprises from about 20 toabout 90%, by weight, component (b)(i) is a mixture of an elastomericblock copolymer of styrene and butadiene of thepoly(styrene-butadiene-styrene) type and a hydrogenated derivativethereof and (ii) is polyethylene, and (b)(i) and (ii) comprise fromabout 5 to about 30% by weight and the styrene homopolymer or randomcopolymer resin component is a homopolystyrene or a rubber modifiedpolystyrene and comprises up to about 60% by weight of the total weightof the resinous components in said composition.
 17. A composition asdefined in claim 1 including up to about 25% by weight of a plasticizer.18. A composition as defined in claim 17 wherein said plasticizer istriphenyl phosphate.
 19. A reinforced composition as defined in claim 1including a reinforcing amount of fibrous glass.